v1.29.0

Added

• claims_root_route(site) -> bool | None hookspec in
  bragi.hookspecs. Plugins (typically themes) return True if they
  handle / for this site, so the admin chrome can tell when a
  theme-provided home overrides the default welcome fallback.
  Stability-contract covered.

Changed

• bragi.contrib.admin_notices's welcome-fallback detector now
  consults claims_root_route instead of the v1.28.1 heuristic
  ("any non-default site.theme suppresses"). Custom themes that
  don't implement the new hook will now correctly fire the
  welcome_fallback notice if their site is otherwise unconfigured:
  the v1.28.1 false-negative protection is gone. Themes that
  override / should add a claims_root_route hookimpl returning
  True; see bragi-theme-zelda for the reference shape. Closes #389.